US Patent Application 2007/0009124 discloses a hearing aid system comprising a left-ear hearing aid, a right-ear hearing aid and a number of auxiliary devices. The hearing aids and the auxiliary devices together form a wireless network, via which they communicate with each other. Start-up of the network and admission of new devices to the network are controlled by a network master, which engages in an initialisation procedure with the new device(s). The network master is preferably one of the hearing aids, because this device is assumed to be always present on the network.
Objects in a hearing device user's environment disturb the radio signals transmitted and received by the hearing devices, when the hearing devices are in place at or in the user's ears. Consequently, the quality of the wireless communication between the hearing devices and the other devices on the network varies when the user moves his head. Such variations may lead to temporal gaps in the communication, and the duration of the gaps may vary from a few fractions of a second to several seconds or even minutes. The gaps may cause pauses and/or delays in audio signals presented to the user, e.g. during streaming of a television audio signal to the hearing devices. For a user of a binaural hearing system, such pauses and delays may be perceived as if sound sources disappear or shift their locations abruptly, which may be very annoying. Such effects may be even more pronounced, when the pauses or delays affect the left-ear and the right-ear hearing device differently. Furthermore, in a hearing system which communicates settings of one of the hearing devices to the other hearing device via radio signals, the gaps may cause the hearing devices to become temporarily unsynchronised, which may produce similar or other annoying audible effects.
In connection-based networks, such as the one described in the prior art mentioned above, gaps of longer duration may further lead to devices becoming disconnected from the network. To recover from the effects of such a long gap and allow the disconnected devices to participate on the network again, an initialisation procedure must be executed. The execution of the initialisation procedure may prolong pauses and/or delays in the audio signals presented to the user, thus worsening the problem. The execution of the initialisation procedure may take longer time if several devices become disconnected at the same time, e.g. if the network master is unreachable during a long gap.